Celebrate an Australian astronomy star

In 1988, Bob Hawke was the prime minister, Kylie Minogue was on the hits list, and one of the world's top radio telescopes opened for business. Ron Ekers celebrates 25 years of discovery at the Australia Telescope Compact Array.

In 1988, Australia marked the bicentenary of European settlement, and there was a mood of (sometimes contentious) nationalism.

The Queen opened the new Parliament House in Canberra, while Sydney got a new football stadium (now the Allianz Stadium). And on 2 September, Prime Minister Bob Hawke opened a new radio telescope near Narrabri, NSW: CSIRO's Australia Telescope Compact Array.

This is a set of six dishes — an array — that work together as one, much larger, telescope. Astronomical studies of the southern sky were among the reasons for the voyage that lead Captain James Cook to discover the continent's east coast. The telescope was funded as a Bicentennial project, acknowledging Australia's pioneering role in astronomy but looking towards the future.

I was there for the event, having been lured back to Australia to become the first director of a new organisation set up to run the telescope, CSIRO's Australia Telescope National Facility (now part of CSIRO's Astronomy and Space Science division).

The telescope at Narrabri has been one of Australia's most successful scientific facilities — and it is getting better, and more productive.

Last year, for instance, the telescope generated more scientific papers than during any previous year of its existence. And it's operated as a national and international facility, something I have always believed in.

In fact, the chance to implement this philosophy in Australia was one of the major attractions of the job.

About 500 researchers a year use the telescope. Some are in-house CSIRO astronomers; more come from other Australian institutions; three-quarters of them are from overseas.

This "open skies" policy is common in the astronomical community. It's the basis on which, for instance, Australian researchers can use the Hubble Space Telescope or any of NASA's other space telescopes. They apply for time on the telescope and a committee assesses the proposed science on its merits. Having telescopes with an "open skies" policy in Australia is our membership card for the broader international community.

The Compact Array is "oversubscribed" — there is about twice as much demand for time on it as can be met (even though it works around the clock). So the science proposals have to be competitive, at a world level.

The researchers who write the proposal (they nearly always work in teams) and then actually use the telescope get first dibs on their data — but only for a certain time. After that it's open to anybody who wants to re-analyse it. Which they often do, using it for new purposes.

Cracking mysteries

What has the Compact Array achieved? Its most highly cited paper and, I think, one of its most exciting achievements, was about helping to crack a problem in astronomy that had lasted for decades.

That problem was the cause of mysterious flashes of gamma rays that were seen going off all over the sky, at the rate of one or two each day. They were discovered in 1967 by military satellites that had been put up to look for signs of nuclear tests: instead, they found a new cosmic phenomenon!

These gamma-ray bursts are the most powerful explosions we know of in the universe. Dozens of theories were put forward to explain them. By the early 90s astronomers were cataloguing them, registering their position and time. But the early space telescopes that recorded the flashes couldn't locate their positions very well, so it was hard to see what other phenomena they could be linked to.

Then in 1998 the BeppoSax satellite spotted a gamma-ray burst and the Compact Array was able to see it and link it to a supernova that had just gone off. This led directly to the understanding that supermassive black holes could be formed from a special type of stellar explosion called a hypernova.

There have been many such moments with the Compact Array. Just a couple of months ago, we were studying a very rare kind of star, a magnetar, which is very close to the black hole at the centre of our galaxy, and which can be used to monitor how fast the black hole is 'feeding'. Also recently, we've been studying the formation of galaxies halfway across the universe, seeing a pattern that we think will tell us what triggers their stars into life.

International success

The raw measures of success — publication rates and citation rates — put the Compact Array among the top few telescopes of its kind in the world. In a 2008 study the Compact Array ranked second in the world only to the much larger Very Large Array (VLA) telescope in the USA.

Three major upgrades and various other technical tweaks have kept the Compact Array at the top of its game. In fact, it is better than ever: more sensitive to faint signals, and able to handle signals over a greater range of radio frequencies. For astronomers, this means being able to detect things they couldn't see before, and being able to get data in faster. We are world leaders in this technology, with a body of extremely skilled staff.

Not only astronomers have benefited from the Compact Array. A follow-up study has shown that when CSIRO's research on radio antennas was transferred to commercial partners in the late 1980s, the benefit-to-cost ratio was 2:1 overall. In the case of antennas built for export, the benefit-to-cost ratio was more than 4:1.

The Compact Array's success cemented Australia's international reputation in radio astronomy and significantly enhanced Australia's bid to host the international Square Kilometre Array radio telescope. And it has shown the world that Australia can run a successful international science facility.

Success of this nature comes from two things. The first is long-term, sustained investment in people and facilities, developing skills and knowledge, upgrading and changing. The second is an openness to the world, bringing in new ideas, new practices, new people. These factors are compatible, and they are both necessary.

Then and now

To that I would add flexibility. When the Compact Array was designed, the Hubble Space Telescope hadn't been launched, and neither had several of NASA's other space telescopes.

We weren't aware of the existence of dark energy: that came along in 1998. One of the phenomena the Compact Array now studies — systems of stars orbiting black holes that emit both x-rays and radio waves — hadn't been discovered. The telescope's designers didn't know that we'd be studying those, but they built in the flexibility to do it — often at very short notice, when these systems flare into activity. The telescope has even been used to put a limit on the number of ultra-high-energy cosmic neutrinos, by studying the radio emission they give off when they hit the Moon.

So on 2 September we can look back with pride. There were some opportunities we missed, and some things I wish we had done differently. But tucked away in northwest New South Wales we have a telescope of world standing.

Just as Australians know about Parliament House in Canberra, or the Sydney Football Stadium, they should know about this.

About the author:Professor Ron Ekers is a CSIRO Fellow and an Adjunct Professor at Curtin University in Perth, and at the Raman Research Institute in India. He was the first director of the Australia National Telescope Facility. Ron has chaired a number of bodies, including the International Steering Committee of the Square Kilometre Array radio telescope, and is a past President of the International Astronomical Union, the organisation representing the world's professional astronomers.

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